Try not to get too upset, I know it's difficult but anything you do or say now can have enormous implications later As I said, I've been there. It's terrible, but don't make it worse by behaving badly yourself.

Oh, mate - its going to cut you up something proper, but try and keep it together, and be strong for your daughter, as she's the one who needs lots of love and to know you care a lot about her right now.

Keep an eye on Netmums for the inevetable "I left my husband and now my boyfriend doesn't want to know, AIBU?" thread

going through a simalar situation at the moment(only no kids).married 10 years together 13.After months of distance,i found out she was having an affair,with a guy who works for the same company as me.she said it was a one off ,but after ending our marrige,she has admited its fairly serious with this guy.
I myself feel alot more together since we split up,blamed myself,for a while,but not anymore,have no malice towards her,(very different towards him).as previous posts have said be strong for your daughter.

Tonight she is angry and not talking to me because I am going out for a drink with my mates instead of 1: sitting at home ignoring each other, or 2: sitting at home arguing or 3: going out together and without doubt having a massive argument. I don't want to go out for a drink or a meal with who I consider to be my soon-to-be-ex wife thanks. I don't think I was being brutish or unkind bringing these facts to her attention, given the mess she is intent on causing, but she is furious.

Your wife has a personality disorder. Don't take it personally - as you said your the patsy.

Separation and divorce are all very well - but if you want to remain part of your kids' lives you have to maintain some kind of functional relationship with your ex

A friend of mine, an ex US Army Ranger, managed to convince the court his wife was bat-shit crazy and got full custody of his children - she tried to tell the court he was an abusive drunk (which he wasn't) and between his intelligent behaviour and his good lawyer they turned it round on her. It can be done. During the breakup she continually tried to test him to breaking point to see if she could make him fly off the hook and do something that would see him lose the children or go to prison. Instead, he calmly documented all the emotional abuse for court. I can't remember the exact details as it was drawn out over many months.

So I can't stress this enough, the OP needs to do his best to keep his cool. Stay calm, write down everything she say's to you in a journal for analysis by lawyers/shrinks and hit record on your smartphone if she starts raging out.

She's back this morning feeling very sorry for herself. Apparently nothing physical as happened between her and this man; this has all been a big ego massage for her and has happened since we first discussed our problems, and is not the catalyst for them. Apparently he started paying her attention at the gym and she let it happen.

She says nothing like this has happened before, and she doesn't think it would have gone past the flirting stage with this man, she was looking for a distraction from our other issues.

She says she hates herself for failing me, our marriage and our daughter. She says she has told him never to contact her again, and that she has deleted her facebook account.

She seems sincere; but she seemed sincere when I asked whether there was anyone else or anything at all external to our marriage a number of times in the last month. She seemed sincere when I poured my heart out and said that I suspected something was up due to her recent behaviour, and that I felt paranoid and insecure; and she looked me in the eye and promised me that nothing was happening. I don't know what to think.

well thats brought it into the open, so good for you, she will be feeling bad, who wouldn't, honesty is often the first casualty, but its the one thing that is needed most in these situations-- hold your head high my man, but let her redeem herself if she so wishes.Good luck both

Your posts from a few days ago show you understand you can move on, you can be optimistic about the future.

The best way forward is councelling from Relate or similar (been there done that) as many have posted if you can work this out it will be best for you all and your daughter, it is possible to emerge with stronger relationship. If you try and you cannot then you know you have the strength to move on, its possible to do that and maintain a great relationship with your daughter.

What I would say is don't persist like this with no real progress, it needs to either improve or end.

Been there etc..there are several parallels to what I've been through. I'm lucky, I don't have kids so its been a bit simpler for me.

Your misses sounds really confused, grass is greener and all that. My (nearly) ex wife did the same. Instead of talking about the problems she just went looking for the next best thing. I found out about it in a similar way to you, but when I confronted her she flat denied it. It was the lying that got me. It showed an absolute lack of respect.

If you both REALLY do want to save the marriage you'll need help. Relate or a good counciller. Be prepared for them to help you realise you might be better apart though.

You CAN'T carry on like this.. your head will explode or you will be a miserable shell of a human. It's no way to live.. I did for 12 months and it damn nearly killed me. Work out what you want, not whats best for everyone and talk it through.

I felt quite a sense of relief when she left and then I began to find out what she'd been up to. It was hard, really hard but every day things got better.. and then I met someone brilliant.... life goes on

I couldn't think of anything to say other than "hire a private detective" on the first pages and felt that might make matters worse as her complaint is that you're a control freak, and fan the fire as you do seem to be a little jealous and insecure.

She accuses you of wanting to control everything, you deny it and then go checking her Facebook pages. If she didn't have sex (I'll accept a slightly wider definition than Clinton here) then nothing happened - she didn't lie. She's entitled to male friends and we all flirt.

We all try to seduce on many levels, we like to be liked, admired even, thought attractive, by our peers and the opposite sex. We like to feel free too, even if in reality we work within a mass of constraints such as work, kids, kids' activities, the weather, our partners etc..

Put yourself in her shoes, would you feel happy, carefree and in control of your destiny? I might be barking up the wrong tree but I don't think she's a nut and she may have a point.

Perhaps the OP could be more specific RE the content of the facebook messages?
Give us the juice.
Really if she said something like "I can't wait to **** your **** then **** your big ****" ;I'd be pretty dismayed. If it was more like "You were wearing a nice t-shirt in the gym", then there's grounds for forgiveness.

Have you considered OP that she may have wanted you (consciously or not) to find out? If someone is having an affair (if that's what it is), then they surely don't plaster it all over an external website and/or leave their phone or whatever lying around to be found. It depends as above on what the messages were and also the nuances which you know and clearly I don't.

It would also explain her apparent confusion when she was upset with you going out. She really wanted you to pay her some attention maybe?

Clearly I may be wrong, but on the basis of what you said I would at least consider that.

I'd never take her back as relationships are based on trust and you'll struggle to ever trust her again.

Call me a pessimist but i'd suggest she's told the gym bloke that she's left and he's either told her he just wanted a fling or more likely that he's probably married/in a relationship already. Now she's back with her tail between her legs to her safety net.

It's up to you though isn't it, only you can make the decision to try and save the relationship? Just don't spend the next 10 years with her being miserable just to take the best option for your child, life's too short.

Nothing physical? Sorry I say walk. Adults dont kiss and hold hands. Sorry I'd I wouldn't believe that. Men and women who start affairs hit sex almost immediately upon affirmation of interest. Its like a drug. Sorry.

She also claimed it was over and she was not interested in him... changed phone number blablabla

I didn't trust her from then on and rightly so as I checked her phone a few weeks later (1st time) and found she had been in constant contact with her new fella, she is now married to him and living in my old home.

I'm also happily re-married with a new 1yr old baby daughter and planning for another, i have 2 teenage kids from first marriage.

My advise is move on as quick as possible and get on with your life...

i.e. get on internet and date as many women as physically possible... oh and ride your bike more often too